Research on desulfurization wastewater evaporation: Present and future perspectives

Nowadays wastewater zero emission in power plants has attracted great attention in the world. This paper describes the recent progress in the cooling of flue gas by the evaporation of desulfurization wastewater. The desulfurization wastewater slurry is mixed with pressurized compression air, and then sprayed into flue gas duct between the air pre-heater and electro-static precipitator or separated evaporation tower, to evaporate the wastewater instantaneously using the exhausted heat of flue gas. This process can reduce water consumption in flue gas desulfurization, cut down the traditional disposing expense consumed in desulfurization wastewater treatment, and reduce gypsum rain discharged from stack etc. This paper summarizes the negative impacts due to the omission of gas-gas heater (GGH) and the difficulties in desulfurization wastewater treatment in current power plants, and also points out that desulfurization wastewater evaporation technology is an important way to achieve zero emission of desulfurization wastewater or other high salt concentration wastewater and solve the problems related to omitting GGH. The instant regulation and control mechanism involved in desulfurization wastewater, migration and transformation rules of desulfurization wastewater and other key problems to be solved are also mentioned respectively. Hopefully, through multidisciplinary researches, evaporation treatment technology for desulfurization wastewater or other high salt concentration wastewater in coal-fired power plants will become mature and be applied widely in near future.